Abstract: Multiple Sclerosis (MS) is the most common neurologic disabling disease among young adults, affecting over 400,000 people in the United States and 2.5 million worldwide. Most MS individuals are initially diagnosed with relapsing-remitting MS (RRMS) and then eventually transition to secondary progressive MS (SPMS). When MS individuals enter SPMS, neurologic deficits progressively worsen over time. Approximately 15% of people with MS are initially diagnosed with primary progressive MS (PPMS) and display increasing neurologic deficits without periods of relapse or remission. Almost all the FDA approved therapeutics for MS are for patients with RRMS and there are very limited therapeutic options for people with progressive MS. A key cytokine/chemokine thought to drive the early inflammatory stage of MS to a chronic progressive phase is macrophage migration inhibitory factor (MIF). We have designed a potent biological construct called RTL1000 and a second-generation derivative, DRhQ, that bind tightly to the MIF receptor, CD74, and competitively inhibit MIF binding and its downstream signaling. RTL/DRhQ treatment was also found to promote neuroprotection and reduce the severity of acute and chronic EAE, a mouse model of MS. RTL1000 was found to be safe and well tolerated at doses 60 mg in a Phase I safety trial in patients with either RRMS or SPMS. However, RTL1000 contains the extracellular domains of the MS risk factor, HLA-DR2 and as such, the FDA limited RTL1000 administration in the clinical trial to HLA-DR2 positive patients (~50% of total MS subjects). In order to treat both DR2 positive and negative individuals with progressive MS, we have been advancing the development of DRhQ, which retains the potent immunomodulatory activity of RTL1000 but is HLA invariant and thus, suitable for all patients. In this Phase IIB SBIR application, we will continue to advance DRhQ toward a First-In-Human (FIH) Phase 1 clinical trial by transferring manufacturing methods and know-how to a contract manufacturing organization (CMO) that will enable production of DRhQ under GMP conditions, completing pre-clinical toxicology testing of DRhQ in two animal species, and developing and optimizing assays to determine the bioanalytical and anti-drug antibody responses in preclinical and clinical samples. The data collected during this Phase IIB project will be used to support filing of a clinical Investigational New Drug (IND) application for a FIH study. The success of RTL1000 in reaching a Phase 1 clinical trial gives us confidence that we will achieve similar success with DRhQ.